Abnormality determination apparatus, non-transitory computer readable medium encoded with a program, abnormality determination system and abnormality determination method

ABSTRACT

To provide an abnormality determination apparatus, a computer readable medium, an abnormality determination system and an abnormality determination method which can simply detect an abnormality of a temperature in a machine tool without incurring cost. An abnormality determination apparatus which determines abnormality of a temperature sensor in a plurality of machine tools, in which the plurality of machine tools is equivalent machine type, is arranged in equivalent environments, are provided with a temperature sensor at equivalent positions, the abnormality determination apparatus including: a temperature data acquisition unit which acquires temperature data outputted by the temperature sensors from each of the plurality of machine tools; a comparison unit which compares the temperature data acquired by the temperature data acquisition unit; and an abnormality determination unit which determines abnormality of the temperature sensor based on a comparison result by the comparison unit.

This application is based on and claims the benefit of priority fromJapanese Patent Application No. 2018-016178, filed on 1 Feb. 2018, thecontent of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the invention

The present invention relates to an abnormality determination apparatus,a non-transitory computer readable medium encoded with a program,abnormality determination system and abnormality determination methodwhich determines abnormalities in the temperature sensors of a pluralityof machine tools.

Related Art

In a machine tool, machining dimensional error occurs due toenvironmental ambient temperature change and heat generation of themachine tool such as cutting heat. For this reason, thermal displacementcompensation technology which compensates the machining dimensionalerror arising due to heating of the machine tool is being used. Astechnology which compensates the thermal displacement due to heatgeneration of this machine tool, for example, there is technology whichmonitors the state of the machine using a plurality of temperaturesensors, and estimates the thermal displacement. This generally installsa temperature sensor to the machine tool, and estimates the thermaldisplacement amount from the output of the temperature sensor. In an FA(Factory Automation) environment in which this temperature sensor isused, abnormalities tend to occur in the temperature sensor compared tonormal usages by the influences such as cutting fluid and chips. In thecase of there being an abnormality in the temperature sensor, it is notpossible to obtain normal temperature output, from the temperaturesensor. Then, in the case of using the output from an erroneoustemperature sensor, it is not possible to estimate an accurate thermaldisplacement amount, and there is concern over negatively impactingmachining.

In the case of an abnormality such as disconnect occurring in thetemperature sensor, since the temperature sensor will output anincorrect value, it is possible to determine an abnormality in thetemperature sensor. However, even if the temperature sensor outputs anincorrect value due to aging degradation or the like, it is not possibleto perform. abnormality detection with the temperature sensor ormeasurement instrument alone. In this regard, Patent Documents 1 and 2disclose methods of detecting abnormalities in a temperature sensorused. in the thermal displacement compensation of a machine tool, forexample. With the methods described in Patent Documents 1 and 2, aplurality of temperature sensors is arranged at different positions ofthe machine tool. Then, in the case of variation in detectedtemperatures of the temperature sensor exceeding a limiting value, or acase of estimating the output of another temperature sensor from theoutput of one temperature sensor, and as a result of comparing,exceeding a limiting value, it determines as an abnormality.

Patent Document 1: Japanese Unexamined Patent Application, PublicationNo. 2008-149415

Patent Document 2: Japanese unexamined Patent Application, PublicationNo. 2008-142844

SUMMARY OF THE INVENTION

However, the methods described in Patent Documents 1 and 2 had toarrange a plurality of temperature sensors in the machine tool. Inaddition, since the heating state will differ depending on the positionat which installing the temperature sensor, a scheme related to theposition at which installing the temperature sensors has also beennecessary. Furthermore, a technique such as installing a plurality oftemperature sensors at the same location has been considered in order todetect an abnormality in a temperature sensor. However, with thistechnique, the number of temperature sensors or measurement instrumentsincreases, and thus cost rises.

The present invention has an object of providing an abnormalitydetermination apparatus, a non-transitory computer readable mediumencoded with a program, abnormality determination system and abnormalitydetermination method which can detect abnormalities in temperaturesensors of a machine tool simply without incurring cost.

An abnormality determination apparatus (for example, the “abnormalitydetermination apparatus 1” described later) according to a first aspectof the present invention determines abnormality of a temperature sensor(for example, the “temperature sensor 7” described later) in a pluralityof machine tools (for example, the machine tool 4 described later), inwhich the plurality of machine tools is equivalent unit type, isprovided in equivalent environments, are provided with temperaturesensors at equivalent positions, and perform equivalent machiningprocesses at equivalent timings; in which the abnormality determinationapparatus includes: a temperature data acquisition unit (for example,the “temperature data acquisition unit 11” described later) whichacquires temperature data outputted by the temperature sensor from eachof the plurality of machine tools; a comparison unit (for example, the“comparison unit 12” described later) which compares the temperaturedata acquired by the temperature data acquisition unit; and anabnormality determination unit (for example, the “abnormalitydetermination unit 13” described later) which determines an abnormalityof the temperature sensor based on a comparison result by the comparisonunit.

An abnormality determination apparatus (for example, the “abnormalitydetermination apparatus 1” described later) according to a second aspectof the present invention determines abnormality of a temperature sensor(for example, the “temperature sensor 7” described later) in a pluralityof machine tools (for example, the machine tool 4 described later), inwhich the plurality of machine tools is equivalent unit type, isprovided in equivalent environments, are provided with temperaturesensors at equivalent positions (for example, the “region 46” describedlater) which do not receive influence from heat generation accompanyingoperation, and perform equivalent machining processes at equivalenttimings; in which the abnormality determination apparatus includes: atemperature data acquisition unit (for example, the “temperature dataacquisition unit 11” described later) which acquires temperature dataoutputted by the temperature sensor from each of the plurality ofmachine tools; a comparison unit (for example, the “comparison unit 12”described later) which compares the temperature data acquired by thetemperature data acquisition unit; and an abnormality determination unit(for example, the “abnormality determination unit 13” described later)which determines an abnormality of the temperature sensor based on acomparison result by the comparison unit.

An abnormality determination apparatus (for example, the “abnormalitydetermination apparatus 1” described later) according to a third aspectof the present invention determines abnormality of a temperature sensor(for example, the “temperature sensor 7” described later) in a pluralityof machine tools (for example, the machine tool 4 described later), inwhich the plurality of machine tools is equivalent unit type, isprovided in equivalent environments, are provided with temperaturesensors at equivalent positions, and is a stopped state no generatingheat; in which the abnormality determination apparatus includes: atemperature data acquisition unit (for example, the “temperature dataacquisition unit 11” described later) which acquires temperature dataoutputted by the temperature sensor from each of the plurality ofmachine tools; a comparison unit (for example, the “comparison unit 12”described later) which compares the temperature data acquired by thetemperature data acquisition unit; and an abnormality determination unit(for example, the “abnormality determination unit 13” described later)which determines an abnormality of the temperature sensor based on acomparison result by the comparison unit.

According to a fourth aspect of the present. invention, in theabnormality determination apparatus as described in any one of the firstto third aspects, the abnormality determination unit may determine thatthe temperature sensor provided in any among the plurality of machinetools is abnormal, in a case or a difference being at least a referencevalue as a result of the comparison.

According to a fifth aspect of the present invention, in the abnormalitydetermination apparatus as described in any one of the first to fourthaspects, a plurality of the temperature sensors may be provided atdifferent positions to each of the plurality of machine tools, and thecomparison unit may compare the temperature data of the temperaturesensors having equivalent installing positions on the machine tools.

A sixth aspect of the present invention may be a non-transitory computerreadable medium encoded. with a program (for example, the “abnormalitydetermination program 16” described later) for causing a computer tofunction as the abnormality determination apparatus as described in anyone of the first to fifth aspects.

An abnormality determination system (for example, the “abnormalitydetermination system 100” described later) according to seventh aspectof the present invention which includes the abnormality determinationapparatus as described in any one of the first to fifth aspects may be aserver in which the abnormality determination apparatus is communicablyconnected to the plurality of machine tools.

An abnormality determination system (for example, the “abnormalitydetermination system 200” described later) according to an eighth aspectof the present invention which includes the abnormality determinationapparatus (for example, the “abnormality determination apparatus 201”described later) as described in any one of the first to fifth aspectsmay provide the abnormality determination apparatus to a machine tool(for example, the “machine tool 204” described later) among theplurality of machine tools.

An abnormality determination method according to a ninth aspect of thepresent invention for temperature sensors (for example, the “temperaturesensor 7” described later) in machine tools (for example, the “machinetool 4” described. later), which are of equivalent unit type and inequivalent environments, determines a temperature sensor having anabnormality by way of a computer (for example, the abnormalitydetermination apparatus 1 described later) comparing temperature data ofthe temperature sensors provided at equivalent positions.

According to the present invention, it is possible to provide anabnormality determination apparatus, a non-transitory computer readablemedium encoded with a program, abnormality determination system andabnormality determination method which can simply detect abnormality ofa temperature sensor in a machine tool, without incurring cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing representing the basic configuration of anabnormality determination system of the present embodiment;

FIG. 2 is a block diagram of an abnormality determination apparatus ofthe present embodiment;

FIG. 3 is a views for explaining about heat generation of a machine toolin the present embodiment;

FIG. 3B is a view for explaining about cooling of a machine tool in thepresent embodiment;

FIG. 4 is a flowchart showing abnormality determination processing ofthe abnormality determination apparatus of the present. embodiment; and

FIG. 5 is a schematic drawing representing a basic configuration of anabnormality determination system of a modified embodiment.

DETAILED DESCRIPTION OF THE INVENTION Embodiment

First, an outline of an embodiment of the present invention will beexplained. The present embodiment relates to a system for determiningabnormality of a temperature sensor, by comparing the outputs of thetemperature sensors provided to a plurality of machine tools in whichthe installing environments are considered equivalent. The output fromthe temperature sensor is transmitted to the abnormality determinationapparatus from each machine tool to which a temperature sensor isinstalled. Then, the abnormality determination apparatus determines anabnormality of a temperature sensor by comparing the temperature datareceived from each machine tool.

Next, an explanation will be made about the configuration of anabnormality determination system 100, which is the present embodiment,by referencing FIG. 1. As shown in FIG. 1, the abnormality determinationsystem 100 includes an abnormality determination apparatus 1, machinetools 4-1, 4-2, . . . , 4-n, and a communication network N. It should benoted that n is an arbitrary natural number of 2 or greater. Then, themachine tools 4-1, 4-2, . . . , 4-n are provided with temperaturesensors 7-1, 7-2, . . . , 7-n. It should be noted that, in the case ofnot distinguishing between the machine tools 4-1, 4-2, . . . , 4-n, theywill hereafter he explained as machine tool 4. In addition, in the caseof not distinguishing between the temperature sensors 7-1, 7-2, . . . ,7-n, they will hereafter be explained as temperature sensor 7.

The plurality of machine tools 4 and the abnormality determinationapparatus 1 are respectively communicably connected to the communicationnetwork N. The communication network N, for example, is a LAN (LocalArea Network) constructed within a factory, Internet, publicationtelephone network, or a combination of these. The specific communicationsystem of the communication network N, whether being a wired connection,wireless connection, etc., is not particularly limited. In addition, theplurality of machine tools 4 and abnormality determination apparatus 1may be connected via an interface.

Next, an explanation will be made for the functional blocks of theabnormality determination apparatus 1 by referencing FIG. 2. Theabnormality determination apparatus 1 is a server which determines anabnormality of a temperature sensor 7 by receiving temperature data froma plurality of the machine tools 4, and comparing the receivedtemperature data. The abnormality determination apparatus 1 includes acontrol unit 10, a storage unit 15, and a communication unit 19. Itshould be noted that the abnormality determination apparatus 1 mayinclude a display device, an output unit as an output device such as awarning lamp and an audio output unit, and an input unit as an inputdevice such as a keyboard and mouse. The control unit 10 may be a CPU(central processing unit), and integrally controls the abnormalitydetermination apparatus 1, by executing various programs which controlthe abnormality determination apparatus 1 stored in the storage unit 15.The control unit 10 includes a temperature data acquisition unit 11, acomparison unit 12 and an abnormality determination unit 13. Each ofthese functional units is realized by the control unit 10 executingprograms stored in the storage unit 15 (i.e. abnormality determinationprogram 16).

The temperature data acquisition unit 11 receives temperature data sentfrom each of the machine tools 4. The temperature data acquisition unit11 may acquire temperature data together with a machine ID(Identification) which identifies the machine tool 4 that is the senderof the temperature data, and a sensor ID which identifies thetemperature sensor 7. Then, the temperature data acquisition unit 11 mayassociate the received temperature data and the machine ID and/or sensorID.

The comparison unit 12 compares the received temperature data. In thecase of a plurality of temperature sensors 7 being provided at differentpositions relative to one machine tool 4, the comparison unit 12compares the temperature data of the temperature sensors 7 provided atequivalent positions. Then, the comparison unit 12, for example,compares whether or not the difference between the plurality oftemperature data sets is less than a reference value.

The abnormality determination unit 13 determines that the temperaturesensor 7 is abnormal in the case of the difference being at least thereference value as a result of comparison by the comparison unit 12.Herein, in the case of comparing the temperature data which is theoutput of the temperature sensors 7 of two machine tools 4, theabnormality determination unit 13 can determine that either one amongthe two temperature sensors 7 which are the senders of temperature datais abnormal. In addition, in the case of comparing three of more sets oftemperature data which are the outputs of the temperature sensors 7 ofthree or more machine tools 4, the abnormality determination unit 13 candetermine which temperature sensor 7 is abnormal according to therespective comparison results of the two sets of temperature data. Inthis case, except for a case of a plurality of temperature sensors 7becoming abnormal at the same time, the abnormality determination unit13 can basically determine the one temperature sensor 7 which isabnormal.

The storage unit 15 is a storage area that stores programs, etc. whichare executed by the control unit 10. The storage unit 15 stores anabnormality determination program 16 which executes various functions ofthe aforementioned control unit 10. In addition, the storage unit 15stores a sensor position storage part 17. The sensor position storagepart 17, for example, stores a machine ID provided by the temperaturesensor 7, and an installing position of the temperature sensor 7 in themachine tool 4, with the sensor ID as a key. The communication unit 19is a communication. control device that performs sending/receiving ofdata with the machine tool 4 via the communication network N.

Next, the machine tool 4 and temperature sensor 7 will be explainedbased on FIGS. 1, 3A and 3B. The machine tool 4 is a machine whichperforms predetermined machining such as cutting on a workpiece such asa component, based on an operation command outputted. by a numericalcontrol device (not shown). This example explains the machine tool 1 ashaving the three translational axes (X, Y, Z axes) which are mutuallyorthogonal, as the drive axes; however, it is not limited thereto.

In the present embodiment, the plurality of machine tools 4 is providedin a factory in which the installing environments are consideredequivalent. Herein, installing environments being equivalent is judgedbased on a predetermined reference set in advance. More specifically,for example, the plurality of machine tools 4 is machines which performwork in the same production line. In addition, even if the plurality ofmachine tools 4 is tools which perform work in different productionlines, so long as being kept at the same temperature by airconditioning, this plurality of machine tools 4 may be equivalentenvironments. These are examples, and not limited thereto. The user canarbitrarily set in advance the predetermined reference. In addition, theplurality of machine tools 4 shall be equivalent unit types. Herein,unit types being equivalent is judged based on a predetermined referenceset in advance. Herein, unit type, for example, indicates the modelnumber, version, options, etc. of the machine tool 4. For example,equivalent unit type refers to the unit type being the same, and mayinclude some version variation such as variation in options. It shouldbe rioted that this is an example, and is not to be limited thereto. Theuser can arbitrarily set in advance a predetermined reference. In thisway, the plurality of machine tools 4 explained in the presentembodiment are tools having equivalent unit type, and provided in afactory in which the installing environments are considered equivalent.

Each of the plurality of machine tools 4 stores a machining program (notshown) for performing machining processing. Herein, the plurality ofmachine tools 4 preferably performs equivalent machining operations;however, the present embodiment does not make essential that theplurality of machine tools 4 performs equivalent machining operations asdescribed later (Example 2 and Example 3). It should be noted thatmachining operations being equivalent is judged based on a predeterminedreference set in advance. For example, the equivalent machiningoperations includes equivalent machining programs, and may be able toperform equivalent machining simultaneously by way of equivalentmachining programs. Herein, for example, equivalent machining programsmay include, other than the machining programs being identical,machining programs which are version variations in the program, and thesubstantial processing being the same, etc. It should be noted. thatthese are examples, and not to be limited thereto. The user canarbitrarily set in advance a predetermined reference. Unless otherwisestated, hereinafter, the installing environments, machine tools andmachining operations matching the predetermined references set inadvance are referred to as equivalent installing environments,equivalent machine tools and equivalent machining operations,respectively.

As shown in FIG. 1, the plurality of machine tools 4 has temperaturesensors 7 provided at equivalent positions. Herein, equivalent positionsrefer to the installing positions of the temperature sensors 7 to themachine tools 4 being the same; however, a shift within a predeterminedrange set in advance is permitted. Herein, there is no limitation in thenumber of temperature sensors 7 provided to one machine tool 4. As shownin FIG. 1, it is sufficient so long as at least one temperature sensor 7is provided to each machine tool 4. The temperature sensor 7 detects thetemperature of the machine tool 4. The temperature sensor 7 tends toreceive or hardly receives the influence of heating depending on themounting position on the machine tool 4.

FIG. 3A is a view of the machine tool 4 seen from the X-axis direction.The machine tool 4 includes various motors including a main axis motor40 a, X-axis motor 40 b, Y-axis motor 40 c, and Z-axis motor 40 d. Dueto the motors being heat sources, in the case of providing thetemperature sensor 7 to a motor region 41 having the motor, thetemperature sensor 7 receives the influence of heating. Next, a motoradjacent area 42 which is adjacent to the motor receives the heatconduction from the heat generation of the motor produced when the motoroperates. For this reason, in the case of providing the temperaturesensor 7 to the motor adjacent area 42, the temperature sensor 7 willreceive the influence of heat generation. In addition, a sliding area 43from operation of the motor generates heat upon a ball screw or linearguide sliding accompanying the operation of the shaft. For this reason,in the case of providing the temperature sensor 7 to the sliding area43, the temperature sensor 7 receives the influence of heat generation.Furthermore, a sliding adjacent area 44 adjacent to the sliding area 43receives heat conduction from the heat generation by sliding. For thisreason, in the case of providing the temperature sensor 7 to the slidingadjacent area 44, the temperature sensor 7 receives the influence ofheat generation.

As shown in FIG. 3B, the machine tool 4 covers the machining space witha cover or the like. The machining space is a space directly subjectedto cutting fluid, subjected to scattered cutting fluid, and filled bymist of cutting oil. For this reason, the machining space receives theinfluence of cutting fluid. The cutting fluid is sprayed from a nozzleprovided to the spindle (not shown), and after applying to theworkpiece, etc. on which performing the machining, is discharged tooutside along with chips. For this reason, a cooling area 45 includingthe inside of the machining space and an adjacent area of the machiningspace tends to receive the influence of cooling by the cutting fluid. Onthe other hand, an area 46 excluding the aforementioned various heatinginfluence areas and cooling area 45 hardly receives the influence ofheating and cooling.

The temperature sensor 7 is a thermistor or the like, and outputs atemperature detection signal. The machine tool 4 digitizes thetemperature detection signal by a known method, and obtains thetemperature data representing the temperature by a numerical value.

Next, examples capable of discriminating the abnormality of atemperature sensor 7 in the present embodiment will be explained.

Example 1

Example 1 is an example of the plurality of machine tools 4 beingequivalent machine tools which are in equivalent installingenvironments, and doing equivalent machining operations. In this case,it can be considered that the plurality of machine tools 4 have equalheat generation states. Consequently, the temperature data indicated bythe temperature detection signal outputted by the temperature sensors 7mounted to the equivalent position will be equal. Therefore, in the caseof the difference being at least the reference value by comparing thetemperature data from the temperature sensors 7 mounted to each of theplurality of machine tools 4, it is possible to determine eithertemperature sensor 7 is abnormal.

Example 2

Example 2 is a case in which the plurality of machine tools 4 isequivalent machine tools which are in equivalent installingenvironments, but the machining operations differ. For example, itcorresponds to a case of each of the plurality of machine tools 4including different machining programs and performing differentmachining, and a case of each of the plurality of machine tools 4including equivalent machining programs, but performing the equivalentmachining at different timings. In this case, the plurality of machinetools 4 are considered to have different heat generation states due tothe machining operations differing. However, for the temperature of aposition which hardly receives the influence of heat generation by themachining operation, the change in temperature from the surroundingenvironment is dominant. Consequently, the temperature data indicated bythe temperature detection signal outputted by the temperature sensor 7mounted at the equivalent position which hardly receives the influenceof heat generation becomes equal. Therefore, in the case of thedifference being at least the reference value by comparing thetemperature data from the temperature sensors 7 mounted to each of theplurality of machine tools 4, it can be determined that eithertemperature sensor 7 is abnormal. Since this example can determineabnormality by mounting the temperature sensor 7 to a position whichhardly received the influence of heat generation, the determination ofabnormality of the heat sensor 7 becomes easy, even if being differentmachining operations.

Example 3

Example 3 is a case of a state in which the plurality of machine tools 4are equivalent machine tools which are in equivalent installingenvironments, and are not generating heat. State of not generating heatrefers to a stopped state in which the respective machine tools 4 arenot operating. In this case, the temperature sensors 7 mounted to theplurality of machine tools 4 will make outputs according to thetemperature of the surrounding environment. Consequently, thetemperature data indicated by the temperature detection signal outputtedby the temperature sensors 7 mounted to equivalent positions are equal.Therefore, in the case of the difference being at least the referencevalue by comparing the temperature data from the temperature sensors 7mounted to each of the plurality of machine tools 4, it is possible todetermine that either of the temperature sensors 7 is abnormal. Thisexample can determine abnormality of the temperature sensor 7, even whena stopped state in which the machine tools 4 are not during operation.

Next, the processing explained in the aforementioned Examples 1 to 3will be explained along with the configuration of the installingenvironment. As a premise, the plurality of machine tools 4 isequivalent machine tools. FIG. 4 a flowchart showing the abnormalitydetermination processing of the abnormality determination apparatus 1.In Step (hereinafter Step S referred to simply as S) 10 in FIG. 4, thecontrol unit 10 (temperature data acquisition unit 11) of theabnormality determination apparatus 1 acquires temperature data byreceiving temperature data sent from each of the machine tools 4.Herein, the temperature data acquisition unit 11 continues to acquiretemperature data sent from the machine tools 4 at the appropriatetiming.

In S11, the control unit 10 specifies the machine tools 4 in theequivalent installing environment. The control unit 10 judges whether ornot being equivalent installing environments based on a predeterminedevaluation criteria set in advance. More specifically, the machine tools4 in the equivalent installing environment may be stored in the storageunit 15 to be associated as machine tools 4 of the equivalent installingenvironment in advance.

In S12, the control unit 10 judges whether or not the plurality ofmachine tools 4 which are in the equivalent installing environment are aheat generating state. The control unit 10, for example, can judgewhether or not the machine tools 4 are a heat generating state byreceiving operating status data from each machine tool 4. The operatingstatus data, for example, is data based on an internal behavior signalof the numerical control device (not shown) acquired at a predeterminedsampling period (For example 1 msec) in time sequence, feed shaftcontrol data detected from the motor of the machine tool 4, spindlecontrol data related to the spindle, etc. In the case of the pluralityof machine tools 4 being a heat generating state (S12: YES), the controlunit 10 advances the processing to S13. On the other hand, in the caseof the plurality of machine tools 4 not being a heat generating state(S12: NO), i.e. being a stopped state, the control unit 10 advances theprocessing to S16.

In S13, the control unit 10 judges whether or not the plurality ofmachine tools 4 which are in the equivalent installing environmentperforms equivalent machining operations. The control unit 10 judgeswhether or not being equivalent machining operations based on thepredetermined evaluation criteria set in advance. In the case of theplurality of machine tools 4 performing equivalent machining operations(S13: YES), the control unit 10 advances the processing to S14. On theother hand, in the case of the plurality of machine tools 4 notperforming equivalent machining operations (S13: NO), the control unit10 advances the processing to S15.

In S14, the control unit 10 (comparison unit 12) compares thetemperature data of temperature sensors 7 provided at equivalentpositions. Herein, in the case of each of the plurality of temperaturesensors 7 being provided to different positions on the machine tool andthe position thereof being equivalent in the plurality of machine tools4, it is sufficient if the control unit 10 compares the temperature dataof the temperature sensors 7 for every position at which the temperaturesensor 7 is provided. Furthermore, if the positions at which thetemperature sensors 7 are equivalent in the plurality of machine tools4, it may be a temperature sensor 7 provided at any positionirrespective of whether receiving the influence of heat generation.Subsequently, the control unit 10 advances the processing to S17.

In S15, the control unit 10 (comparison unit 12) compares thetemperature data of temperature sensors 7 provided at a position hardlyreceiving the influence of heating and cooling. Herein, position hardlyreceiving the influence of heating and cooling, for example, refers tothe area 46 shown in FIG. 3B. It should be noted that, in the case ofthe temperature sensor 7 being provided at a position tending to receivethe influence of heating and cooling of the machine tool 4, since theheat generation extent varies depending on the machining processcontents of each machine tool 4, it is not possible to determineabnormality of the temperature sensor 7. For this reason, in the case ofnot performing equivalent machining operations, it is necessary tocompare the temperature data of the temperature sensors 7 provided at aposition hardly receiving the influence of heating and cooling.Subsequently, the control unit 10 advances the processing to S17.

In S16, the control unit 10 (comparison unit 12) compares thetemperature data of temperature sensors 7 provided at equivalentpositions. In S17, the control unit 10 (abnormality determination unit13) determines whether the difference is at least the reference value,as a result of comparing temperature data. In the case of the differencebeing at least the reference value (S17: YES), the control unit 10advances the processing to S18. On the other hand, in the case of thedifference being less than the reference value (S17: NO), the controlunit 10 ends the present processing. In other words, case of thedifference being less than the reference value indicates all of thetemperature sensors 7 provided to the plurality of machine tools 4 notbeing abnormal. It should be noted. that, in the case of the differencebeing less than the reference value, the control unit 10 shall end thepresent processing; however, it may be configured so as to end thepresent processing after making report of the fact of being normal.

In S18, the control unit 10 (abnormality determination unit 13)determines at least one among the temperature sensors 7 provided to theplurality of machine tools 4 is abnormal. It should be noted that thecontrol unit 10 may feedback the determination results to the machinetools 4, and may output to an output unit (not shown) of the abnormalitydetermination apparatus 1. As an output method, it can be considered tooutput an error on a screen, turn on a warning lamp, and make an outputby sound. Subsequently, the control unit 10 ends the present processing.

According to the above, the abnormality determination system 100 caneasily detect abnormality of the temperature sensor 7 provided atequivalent positions without incurring cost, so long as the plurality ofmachine tools 4 provided in equivalent installing environments areequivalent machine tools.

More specifically, in the case of the machine tool 4 being the heatgeneration state, i.e. case of the power source being turned on, themachining program actually being executed and a machining process beingperformed, for example, when performing equivalent machining operations,the temperature data detected by the temperature sensors 7 provided atequivalent positions of each machine tool 4 is considered to indicatealmost the same temperature. For this reason, as a result of comparing aplurality of sets of temperature data, in the case of the differencebeing at least the reference value, it is possible to determine at leastone temperature sensor 7 as being abnormal.

In addition, in the case of the machine tools 4 being a heat generationstate, i.e. case of the power source being turned on, the machiningprogram. actually being executed and a machining process beingperformed, even when the processing is being executed by differentmachining programs, so long as being temperature sensors 7 provided at aposition hardly receiving the influence of heat generation, thetemperature data received from each machine tool 4 is considered toindicate almost the same temperature. Consequently, as a result ofcomparing a plurality of sets of temperature data, in the case of thedifference being at least the reference value, it can be determined asat least one temperature sensor 7 being abnormal.

Furthermore, in the case of the machine tool 4 not being a heatgeneration state, i.e. case of only the power source for sending databeing turned on, and electric power not being supplied to the motor,etc., even if temperature sensors 7 provided at any position of themachine tool 4, the temperature data detected by a temperature sensor 7provided at an equivalent position is considered to indicate almost thesame temperature. For this reason, as a result of comparing a pluralityof sets of temperature data, in the case of the difference being atleast the reference value, it can be determined as at least onetemperature sensor 7 being abnormal.

Due to receiving the temperature data from a plurality of machine tools4, the abnormality determination apparatus 1 can centrally manage thestates of the temperature sensor 7 including abnormality. Theabnormality determination apparatus 1 includes a sensor position storageunit 17. The sensor position storage unit 17 includes a sensor ID oftemperature sensors 7 which includes the positions of the temperaturesensors 7, and the machine ID of the machine tools 4. So long as havinginformation related to the mounting position of the temperature sensor7, installing position and model type of machine tool 4 in this sensorposition storage unit 17, the abnormality determination apparatus 1 canconfirm whether the temperature sensors 7 are mounted at equivalentpositions, whether in equivalent installing environments, and whetherbeing equivalent machine tools by referencing the sensor positionstorage unit 17, and thus is convenient.

The programs including the abnormality determination program used in thepresent invention can be stored using various types of non-transitorycomputer readable media, and supplied to a computer. Non-transitorycomputer readable media includes various types of tangible storagemedia. Examples of non-transitory computer readable media includemagnetic media (for example, flexible disks, magnetic tape, hard diskdrive), magneto-optical recording media (for example, magneto-opticaldisk), CD-ROM (Read Only Memory), CD-R, CD-R/W, and semiconductor memory(for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM),flash ROM, RAM (random access memory)). In addition, the program may beprovided to a computer by way of various types of transitory computerreadable media. Examples of transitory computer readable media includeelectrical signals, optical signals and electromagnetic waves.Transitory computer readable media can provide programs to a computervia wired communication paths such as electrical wires and opticalfiber, or a wireless communication path.

In addition, the aforementioned embodiment is a preferred embodiment ofthe present invention; however, it is not to limit the scope of thepresent invention to only the above-mentioned embodiment, andrealization is possible in a form achieved by conducting variousmodifications in a scope not departing from the gist of the presentinvention.

Modified Example 1

In the aforementioned embodiment, the abnormality determinationapparatus 1 communicably connected to the plurality of machine tools 4is explained as determining abnormalities of temperature sensors 7;however, it is not limited thereto. As shown in FIG. 5, it may be anabnormality determination system 200 including an abnormalitydetermination apparatus 201 in one machine tool 204, and communicablyconnecting the machine tool 204 and other machine tools 4 (4-2, . . . ,4-n) in an installing environment equivalent with this machine tool 204by way of the communication network N. Even if being the abnormalitydetermination system 200, it is possible to determine abnormalities ofthe temperature sensors 7 by way of the abnormality determinationapparatus 201.

Modified Example 2

In the aforementioned embodiment, a system in which the machine tool 4generates temperature data based on the temperature detection signalfrom the temperature sensors 7 is explained as an example; however, itis not limited thereto. The machine tool 4 may transmit the temperaturedetection signal as is to the abnormality determination apparatus 1, andgenerate temperature data from the temperature detection signal in theabnormality determination apparatus 1.

EXPLANATION OF REFERENCE NUMERALS

-   1, 201 abnormality determination apparatus-   4, 4-1, 4-2, . . . , 4-n, 204 machine tool-   7, 7-1, 7-2, . . . , 7-n temperature sensor-   10 control unit-   11 temperature data acquisition unit-   12 comparison unit-   13 abnormality determination unit-   15 storage unit-   16 abnormality determination program-   17 sensor position storage unit-   41 motor area-   42 motor adjacent area-   43 sliding area-   41 sliding adjacent area-   45 cooling area-   46 area-   100, 200 abnormality determination system

What is claimed is:
 1. An abnormality determination apparatus whichdetermines abnormality of a temperature sensor in a plurality of machinetools, wherein the plurality of machine tools is equivalent unit type,is provided in equivalent environments, are provided with temperaturesensors at equivalent positions, and perform equivalent machiningprocesses at equivalent timings, wherein the abnormality determinationapparatus comprises: a temperature data acquisition unit which acquirestemperature data outputted by the temperature sensor from each of theplurality of machine tools; a comparison unit which compares thetemperature data acquired by the temperature data acquisition unit; andan abnormality determination unit which determines an abnormality of thetemperature sensor based on a comparison result by the comparison unit.2. An abnormality determination apparatus which determines abnormalityof a temperature sensor in a plurality of machine tools, wherein theplurality of machine tools is equivalent unit type, is provided inequivalent environments, are provided with temperature sensors atequivalent positions which do not receive influence from heat generationaccompanying operation, wherein the abnormality determination apparatuscomprises: a temperature data acquisition unit which acquirestemperature data outputted by the temperature sensor from each of theplurality of machine tools; a comparison unit which compares thetemperature data acquired by the temperature data acquisition unit; andan abnormality determination unit which determines an abnormality of thetemperature sensor based on a comparison result by the comparison unit.3. An abnormality determination apparatus which determines abnormalityof a temperature sensor in a plurality of machine tools, wherein theplurality of machine tools is equivalent unit type, is provided inequivalent environments, are provided with temperature sensors atequivalent positions, and is a stopped state not generating heat,wherein the abnormality determination apparatus comprises: a temperaturedata acquisition unit which acquires temperature data outputted by thetemperature sensor from each of the plurality of machine tools; acomparison unit which compares the temperature data acquired by thetemperature data acquisition unit; and an abnormality determination unitwhich determines an abnormality of the temperature sensor based on acomparison result by the comparison unit.
 4. The abnormalitydetermination apparatus according to claim 1, wherein the abnormalitydetermination unit determines that the temperature sensor provided inany among the plurality of machine tools is abnormal, in a case of adifference being at least a reference value as a result of thecomparison.
 5. The abnormality determination apparatus according toclaim 1, wherein a plurality of the temperature sensors is provided atdifferent positions to each of the plurality of machine tools, andwherein the comparison unit compares the temperature data of thetemperature sensors having equivalent installing positions on themachine tools.
 6. A non-transitory computer readable medium encoded witha program for causing a computer to function as the abnormalitydetermination apparatus according to claim
 1. 7. An abnormalitydetermination system comprising the abnormality determination apparatusaccording to claim 1, wherein the abnormality determination apparatus isa server which is communicably connected to the plurality of machinetools.
 8. An abnormality determination system comprising the abnormalitydetermination apparatus according to claim 1, wherein the abnormalitydetermination apparatus equipped to one machine tool among the pluralityof machine tools.
 9. An abnormality determination method for temperaturesensors in a plurality of machine tools, which are of equivalent unittype and in equivalent environments, the method comprising determining atemperature sensor having an abnormality, by way of a computer comparingtemperature data of the temperature sensors provided at equivalentpositions.